Problem: Solve for $q$ : $-7 + q = 15$
Explanation: Add $7$ to both sides: $ \begin{eqnarray} \\ -7 + q &=& 15 \\ \\ {+7} && {+7} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{-7 + q} &\hphantom{=}& \hphantom{15} \\ q &=& 15 {+ 7} \\ \end{eqnarray} $ Simplify. $ q = 22$